The high-definition multimedia interface (HDMI™) is a compact audio/video connector interface for transmitting uncompressed digital streams. The HDMI connects digital audio/video (or multimedia) sources (e.g., a set-top box, a DVD player, a personal computer, a video game console, etc.) to a compatible digital audio device and/or video monitor such as a digital television.
An exemplary block diagram of an HDMI link 100 is shown in FIG. 1. A multimedia source 110 transmits high speed data using transition minimized differential signaling (TMDS®) characters. The TMDS characters are high-speed signals encapsulating video, audio, and auxiliary data and are carried over three TMDS channels 130-1, 130-2, and 130-3. A multimedia sink 120 receives the TMDS characters and converts them into digital video and audio streams, data packets, and control signals.
A clock, typically running at the video pixel rate, is transmitted on a clock channel 140 and is used by the multimedia sink 120 as a frequency reference for data recovery on the three TMDS channels 130-1, 130-2, and 130-3. In addition, configuration, system-level control, management and status information is exchanged between the multimedia source 110 and the multimedia sink 120. The system-level control includes a display data channel (DDC) and a consumer electronics control (CEC) which are transmitted over channels: SCL 150, SDA 160, and CEC 170. Signals transported over the SCL 150, SDA 160, and CEC 170 channels are considered as low-speed signals. A hot plug detector (HPD) signal 180 is sent from the multimedia sink 120 and multimedia source 110.
As illustrated in FIG. 2A, the various high speed multimedia signals are generated using a multimedia transmitter 210 and decoded using a multimedia receiver 220. Typically, the transmitter 210 and receiver 220 are implemented in an integrated circuit (IC). The output/input high speed multimedia signals from the transmitter/receiver are carried over conducting wires 230-1 to 230-4, on a printed circuit board (PCB) 240, to a multimedia interface connector 250, e.g., an HDMI connector. Specifically, the wires 230-1, 230-2, and 230-3 are respectively connected to pins 251, 252 and 253 in the connector 250. The pins 251, 252 and 253 are connected to channels carrying high-speed multimedia signals (e.g., the TMDS channels 130-1, 130-2, and 130-3). The wire 230-4 is coupled to the clock's pin 254 of, e.g., the clock channel 140. Typically, each conducting wire 230-1 to 230-4 is a differential pair. As can be noted there is a one-to-one connection between each pin in the connector 250 to its respective output of transmitter's 210 output or an input receiver's 220 input.
The performance of a multimedia interface system, and in particular an HDMI system, strongly depends on the quality of the physical infrastructure carrying the signals between the transmitter 210 and receiver 220. Specifically, if the conducting wires 230 are not directly wired between the output/input of the transmitter/receiver and the connector 250 the quality of the signals, carried over the wires 230-1 to 230-4, is significantly reduced. Specifically, the signal integrity and signal-to-noise-ratio (SNR) of at least high-speed multimedia signals are affected.
As illustrated in FIGS. 2B and 2C, in some cases, the wires 230-1 to 230-4 carrying the high-speed multimedia signals are crossed due to mechanical constraints that determine the locations of the connector 250, transmitter 210, receiver 220. For example, in FIG. 2B, the conducting wires 230-1 to 230-4 are crossed on the PCBs 240 due to the location of the connector 250 and the receiver 220 and transmitter 210. In FIG. 2C, the conducting wires 230-1 to 230-4 between the transmitter 210 and pins of the connector 250 are crossed. Typically, in such designs the signals are routed through different metal layers and vias on the PCBs 240. As a result, the quality of the signals is significantly reduced.
Therefore, it would be advantageous to have a solution that would enable a direct connection between a circuit for processing high-speed multimedia signals and a multimedia connector.